1. Field of the Invention
The present invention relates to a photovoltaic module wherein frames are mounted to a periphery of a photovoltaic module body including a plurality of solar cells.
2. Description of the Prior Art
Solar cells are expected to serve as a novel energy source because they can convert light energy from the sun directly into electric energy, the sun providing an inexhaustible supply of clean energy.
Each solar cell provides a small output of several watts. Therefore, a common practice to use such solar cells as a source of electric power for household use or for use in building or the like is to connect a plurality of solar cells in series or in parallel thereby forming a photovoltaic module the output of which is increased to hundreds of watts. Such a photovoltaic module is disclosed in JP2007-95819(A), for example.
FIG. 10 is a plan view showing a conventional photovoltaic module. The conventional photovoltaic module is described with reference to FIG. 10.
As shown in FIG. 10, a plurality of solar cells 800 are electrically interconnected by means of a wiring material 802 made of a conductive material such as copper foil and are sealed between a surface member having translucency, such as glass or translucent plastic, and a backside member made of weather-resistant film with a sealing material having translucency, such as EVA (Ethylene Vinyl Acetate) having excellent weather resistance and moisture resistance.
The plural solar cells 800 are connected in series by means of the wiring material 802 so as to constitute a string 810 as a unit. These strings 810, 810 are interconnected by means of an interconnecting wiring or a so-called crossover wiring 811. Further, the strings are connected with a leading line (not shown) for extracting the output from these solar cells 800.
A photovoltaic module body 820 is formed in this manner. A frame 850 formed of an aluminum material or the like is mounted to a periphery of the photovoltaic module body.
The strength of such a photovoltaic module is assured not only by the surface member but also by the frames 850. This negates the need for increasing the thickness of the surface member in a case where the photovoltaic module is increased in size. Therefore, the weight increase of the photovoltaic module can be lessened so that the photovoltaic module becomes easier to handle. Another advantage is that the amount of transmitted light is increased by virtue of the decreased thickness of the surface member so that power generation efficiency can be increased.
By the way, as shown in FIG. 11, the above-described frames 850 are coupled and fixed to each other by press-inserting a securing member called corner piece 830 into respective mounting portions 851 thereof located at a corner defined by the frames 850.
In consideration of the increase in the weight and cost of the photovoltaic module, the thickness of the frame 850 is reduced as much as possible. A conventional frame 850 commonly used has a thickness of 1.5 mm, for example.
In some cases, the corner piece 830 press-inserted into the above-described frames 850 may deform the frames 850 so as to produce a gap 855, as shown in FIG. 12.
When the gap 855 is produced, an adjustment work is required for closing the gap 855, resulting in a drawback of lowered workability.